-The Onyx is the only finger pulse oximeter with scientifically proven accuracy and is tested for use on fingers, thumbs and toes.-Proven Accuracy : Scientifically proven accuracy in the widest range of patients.-Reliable Results : Accurate readings on challenging patients due to low perfusion and darker skin tones. -Tested in motion.-Versatile : Units work on pediatric to larger adult patients and can be used on fingers, thumbs or toes.-Cost Efficient : 4-year warranty and up to 6,000 spot checks on two AAA batteries.